Example of str in builtins.py

Hello everyone, I’ve just stopped at the Python source code of str class and I see a few str functions, such as capitalize and encode. However, there is no implementation there.

Thus, could anyone point me out where are those methods being implemented in Python? I have heard that they are implemented in Python’s interpreter, but I can’t find it anywhere.

Thanks for helping me!

I have tried to see where str class functions such as capitalize and encode being implemented.